The present invention relates, in general, to electronics and, more particularly, to potentiometers and methods for manufacturing potentiometers.
Potentiometers are electronic circuits that provide a variable impedance between two nodes. Digital potentiometers are electronic circuits that provide a variable impedance in accordance with a digital signal. A digital potentiometer has a fixed value impedance connected between two reference terminals. This impedance is provided by a string of impedance devices that can be selectively connected to a third terminal, called a wiper terminal, through electronic switches that are controlled by digital signals. Digital potentiometers can be used in digital-to-analog converters and as replacements for mechanical potentiometers and rheostats.
The fineness of adjustment, resolution, or “granularity” of a digital potentiometer is typically determined by the number of digital bits used for the selection of the desired wiper position. For instance, an eight bit wiper address allows for 28, i.e., 256, different wiper impedance selections or wiper positions. A disadvantage of finer adjustment granularity (more digital bits) is a rapid increase in the number of components such as resistors, switches, decoding gates, or other logic devices required for implementation. The increase in the number of components typically results in larger and more expensive devices.
Accordingly, it would be advantageous to have a method and circuit for adjusting an impedance. It would be of further advantage for the method and circuit to be cost efficient to implement.